This present application relates generally to apparatus, methods and/or systems pertaining to controlling flow through concentric hollow passages. More specifically, but not by way of limitation, the present application relates to apparatus, methods and/or systems pertaining to an annular style check valve that passively controls two independent supply flow streams to a common outlet flow stream.
In certain industrial applications, there is a need for controlling the flow of supply lines that are configured in a concentric arrangement. While certain conventional systems may be configured to functional perform this tasks, they are bulky, inefficient, expensive and/or require active control. As a result, there remains a need for improved apparatus, methods and/or systems relating to the more efficient and cost effective control of the flows through concentrically arranged supply lines.
For example, the fuel delivery system of certain gas turbine engines have an issue of residual liquid fuel coking and fouling the system. The coking of liquid fuel in fuel lines of gas turbine engines has been a long-standing issue, particularly in those dual-burn engines that bun both a liquid and gaseous fuel. Generally, when the engine is switch from burning a liquid fuel to a gaseous fuel, a residual of the liquid fuel remains in the liquid fuel piping system. Conventional systems generally do not have the capability to remove all of the residual liquid fuel from the pipes within the system and some of the residual remains in pipes that reside near the endcover of the combustor unit and, as a result, experience the elevated temperatures associated with the combustion process. When the liquid fuel is moving through the supply lines, the elevated temperatures do not have time to coke the fuel. However, because the residual liquid fuel is stationary, the elevated temperatures, over time, coke the fuel. As one of ordinary skill will appreciate, this process makes the residual liquid fuel turn gummy or solid, which generally results in significant operational issues and/or an inability of the engine to properly burn the liquid fuel.
Conventional systems have failed to adequately address these issues in a cost-effective and efficient manner. For example, some conventional systems employ remote actuated 2-way and 3-way valve configurations as a replacement for standard check valves. However, these systems proved costly to implement and still do not fully address the coking issue. Efforts to cool the residual liquid fuel have included water-cooled check valves and air-cooled 2-way valves. However, these designs and the associated components generally are costly, result in increased maintenance, and may result in operability risks if not properly installed and maintained. As a result, there is a need for systems and methods that adequately address the coking issue in a cost-effective and efficient manner.